Angular filter by child array

Filter the cast of the Avengers with a custom filter.

HTML

<div ng-app="myApp" class="container">
    <div class="row">
        <input type="text" data-ng-model="number" />
        <div>{{number | ordinal}}</div>
    </div>
</div>

JavaScript

var myApp = angular.module('myApp', []).filter('ordinal', function() {
  return function(input) {
    var date = new Date(input);
    var dayOfMonth = date.getDate();
    var suffix = dayOfMonth;
      var suffixes = ["th", "st", "nd", "rd"];
    var relevantDigits = (dayOfMonth < 30) ? dayOfMonth % 20 : dayOfMonth % 30;
      var suf = (relevantDigits <= 3) ? suffixes[relevantDigits] : suffixes[0];
    return  input+' '+suf;
  }
});